[libibery PATCH] Fix bootstrap

[libibery PATCH] Fix bootstrap

[Nathan Sidwell]

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We now warn on casts to T const.  Applied as obvious to fix bootstrap.

nathan
-- 
Nathan Sidwell

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Index: ChangeLog
===================================================================
--- ChangeLog	(revision 248441)
+++ ChangeLog	(working copy)
@@ -1,3 +1,7 @@
+2017-05-24  Nathan Sidwell  <nathan@acm.org>
+
+	* libiberty.h (ASTRDUP): Adjust cast to avoid warning.
+
 2017-05-19  Eli Zaretskii <eliz@gnu.org>
 
 	* environ.h: Add #ifndef guard.
Index: libiberty.h
===================================================================
--- libiberty.h	(revision 248441)
+++ libiberty.h	(working copy)
@@ -724,7 +724,7 @@ extern void *C_alloca (size_t) ATTRIBUTE
 # define ASTRDUP(X) \
   (__extension__ ({ const char *const libiberty_optr = (X); \
    const unsigned long libiberty_len = strlen (libiberty_optr) + 1; \
-   char *const libiberty_nptr = (char *const) alloca (libiberty_len); \
+   char *const libiberty_nptr = (char *) alloca (libiberty_len); \
    (char *) memcpy (libiberty_nptr, libiberty_optr, libiberty_len); }))
 #else
 # define alloca(x) C_alloca(x)

Re: [libibery PATCH] Fix bootstrap

[Nathan Sidwell]

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On 05/24/2017 08:34 PM, Nathan Sidwell wrote:
> We now warn on casts to T const.  Applied as obvious to fix bootstrap.

And this fixes c-common.c

nathan

-- 
Nathan Sidwell

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2017-05-24  Nathan Sidwell  <nathan@acm.org>

	* c=common.c (field_decl_cmp, resort_field_decl_cmp): Adjust T
	const casts to avoid warning.

Index: c-common.c
===================================================================
--- c-common.c	(revision 248441)
+++ c-common.c	(working copy)
@@ -5866,8 +5866,8 @@ check_builtin_function_arguments (locati
 int
 field_decl_cmp (const void *x_p, const void *y_p)
 {
-  const tree *const x = (const tree *const) x_p;
-  const tree *const y = (const tree *const) y_p;
+  const tree *const x = (const tree *) x_p;
+  const tree *const y = (const tree *) y_p;
 
   if (DECL_NAME (*x) == DECL_NAME (*y))
     /* A nontype is "greater" than a type.  */
@@ -5892,8 +5892,8 @@ pointer operator in resort_data.  */
 static int
 resort_field_decl_cmp (const void *x_p, const void *y_p)
 {
-  const tree *const x = (const tree *const) x_p;
-  const tree *const y = (const tree *const) y_p;
+  const tree *const x = (const tree *) x_p;
+  const tree *const y = (const tree *) y_p;
 
   if (DECL_NAME (*x) == DECL_NAME (*y))
     /* A nontype is "greater" than a type.  */

Re: [libibery PATCH] Fix bootstrap

[Nathan Sidwell]

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On 05/24/2017 08:56 PM, Nathan Sidwell wrote:
> On 05/24/2017 08:34 PM, Nathan Sidwell wrote:
>> We now warn on casts to T const.  Applied as obvious to fix bootstrap.
> 
> And this fixes c-common.c

And fix auto-profile.c

nathan

-- 
Nathan Sidwell

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2017-05-24  Nathan Sidwell  <nathan@acm.org>

	* auto-profile.c (afdo_propagate): Adjust T const cast to avoid
	warning.

Index: auto-profile.c
===================================================================
--- auto-profile.c	(revision 248441)
+++ auto-profile.c	(working copy)
@@ -1377,7 +1377,7 @@ afdo_propagate (bb_set *annotated_bb, ed
   FOR_ALL_BB_FN (bb, cfun)
   {
     bb->count = ((basic_block)bb->aux)->count;
-    if (is_bb_annotated ((const basic_block)bb->aux, *annotated_bb))
+    if (is_bb_annotated ((basic_block)bb->aux, *annotated_bb))
       set_bb_annotated (bb, annotated_bb);
   }
 

Re: [libibery PATCH] Fix bootstrap

[Nathan Sidwell]

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On 05/24/2017 09:13 PM, Nathan Sidwell wrote:
> On 05/24/2017 08:56 PM, Nathan Sidwell wrote:
>> On 05/24/2017 08:34 PM, Nathan Sidwell wrote:
>>> We now warn on casts to T const.  Applied as obvious to fix bootstrap.
>>
>> And this fixes c-common.c
> 
> And fix auto-profile.c

and lto-streamer-out.c, sigh

-- 
Nathan Sidwell

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2017-05-24  Nathan Sidwell  <nathan@acm.org>

	* lto-streamer-in.c (lto_input_data_block): Adjust T const cast to
	avoid warning. 

Index: lto-streamer-in.c
===================================================================
--- lto-streamer-in.c	(revision 248441)
+++ lto-streamer-in.c	(working copy)
@@ -86,7 +86,7 @@ void
 lto_input_data_block (struct lto_input_block *ib, void *addr, size_t length)
 {
   size_t i;
-  unsigned char *const buffer = (unsigned char *const) addr;
+  unsigned char *const buffer = (unsigned char *) addr;
 
   for (i = 0; i < length; i++)
     buffer[i] = streamer_read_uchar (ib);

Re: [libibery PATCH] Fix bootstrap

[Richard Biener]

On May 25, 2017 3:22:18 AM GMT+02:00, Nathan Sidwell <nathan@acm.org> wrote:
>On 05/24/2017 09:13 PM, Nathan Sidwell wrote:
>> On 05/24/2017 08:56 PM, Nathan Sidwell wrote:
>>> On 05/24/2017 08:34 PM, Nathan Sidwell wrote:
>>>> We now warn on casts to T const.  Applied as obvious to fix
>bootstrap.
>>>
>>> And this fixes c-common.c
>> 
>> And fix auto-profile.c
>
>and lto-streamer-out.c, sigh

What's the reason to warn here?!

Richard.

Re: [libibery PATCH] Fix bootstrap

[Nathan Sidwell]

On 05/25/2017 01:29 AM, Richard Biener wrote:
> On May 25, 2017 3:22:18 AM GMT+02:00, Nathan Sidwell <nathan@acm.org> wrote:
>> On 05/24/2017 09:13 PM, Nathan Sidwell wrote:
>>> On 05/24/2017 08:56 PM, Nathan Sidwell wrote:
>>>> On 05/24/2017 08:34 PM, Nathan Sidwell wrote:
>>>>> We now warn on casts to T const.  Applied as obvious to fix
>> bootstrap.
>>>>
>>>> And this fixes c-common.c
>>>
>>> And fix auto-profile.c
>>
>> and lto-streamer-out.c, sigh
> 
> What's the reason to warn here?!

It's a new warning about trying to cast to a const T because the const 
is ignored.

It might be better if the warning only triggered on trying to cast 'T' 
to 'const T' and not trigger casting 'U' to 'const T'?  I dunno.

nathan

-- 
Nathan Sidwell

Re: [libibery PATCH] Fix bootstrap

[Jonathan Wakely]

On 25/05/17 06:54 -0400, Nathan Sidwell wrote:
>On 05/25/2017 01:29 AM, Richard Biener wrote:
>>On May 25, 2017 3:22:18 AM GMT+02:00, Nathan Sidwell <nathan@acm.org> wrote:
>>>On 05/24/2017 09:13 PM, Nathan Sidwell wrote:
>>>>On 05/24/2017 08:56 PM, Nathan Sidwell wrote:
>>>>>On 05/24/2017 08:34 PM, Nathan Sidwell wrote:
>>>>>>We now warn on casts to T const.  Applied as obvious to fix
>>>bootstrap.
>>>>>
>>>>>And this fixes c-common.c
>>>>
>>>>And fix auto-profile.c
>>>
>>>and lto-streamer-out.c, sigh
>>
>>What's the reason to warn here?!
>
>It's a new warning about trying to cast to a const T because the const 
>is ignored.
>
>It might be better if the warning only triggered on trying to cast 'T' 
>to 'const T' and not trigger casting 'U' to 'const T'?  I dunno.

Maybe, although the language is clear that casting to (const T) means
exactly the same as casting to (T) when T is a scalar type. What
benefit is there to saying (const T) if the compiler ignores the
const?  (which the standard says it should, and I implemented in
r248432).

Re: [libibery PATCH] Fix bootstrap

[Jonathan Wakely]

On 25/05/17 12:19 +0100, Jonathan Wakely wrote:
>On 25/05/17 06:54 -0400, Nathan Sidwell wrote:
>>On 05/25/2017 01:29 AM, Richard Biener wrote:
>>>On May 25, 2017 3:22:18 AM GMT+02:00, Nathan Sidwell <nathan@acm.org> wrote:
>>>>On 05/24/2017 09:13 PM, Nathan Sidwell wrote:
>>>>>On 05/24/2017 08:56 PM, Nathan Sidwell wrote:
>>>>>>On 05/24/2017 08:34 PM, Nathan Sidwell wrote:
>>>>>>>We now warn on casts to T const.  Applied as obvious to fix
>>>>bootstrap.
>>>>>>
>>>>>>And this fixes c-common.c
>>>>>
>>>>>And fix auto-profile.c
>>>>
>>>>and lto-streamer-out.c, sigh
>>>
>>>What's the reason to warn here?!
>>
>>It's a new warning about trying to cast to a const T because the 
>>const is ignored.
>>
>>It might be better if the warning only triggered on trying to cast 
>>'T' to 'const T' and not trigger casting 'U' to 'const T'?  I dunno.
>
>Maybe, although the language is clear that casting to (const T) means
>exactly the same as casting to (T) when T is a scalar type. What
>benefit is there to saying (const T) if the compiler ignores the
>const?  (which the standard says it should, and I implemented in
>r248432).

I don't mind removing the warning again if preferred. I thought it was
useful (as we already warn for ignored const in return types).

All I really care about is that the compiler ignores the const, if it
does that without warning that's OK.

Re: [libibery PATCH] Fix bootstrap

[Nathan Sidwell]

On 05/25/2017 07:21 AM, Jonathan Wakely wrote:

> I don't mind removing the warning again if preferred. I thought it was
> useful (as we already warn for ignored const in return types).

Oh yeah, I recall noticing we did that (and noting we didn't warn 
elsewhere).  This new warning seems consistent.

I say leave it in unless the grumbling gets too much for you :)

nathan

-- 
Nathan Sidwell

Re: [libibery PATCH] Fix bootstrap

[Richard Biener]

On May 25, 2017 1:38:36 PM GMT+02:00, Nathan Sidwell <nathan@acm.org> wrote:
>On 05/25/2017 07:21 AM, Jonathan Wakely wrote:
>
>> I don't mind removing the warning again if preferred. I thought it
>was
>> useful (as we already warn for ignored const in return types).
>
>Oh yeah, I recall noticing we did that (and noting we didn't warn 
>elsewhere).  This new warning seems consistent.
>
>I say leave it in unless the grumbling gets too much for you :)

I wonder if we can somehow default to -Wno-error=xyz for such kind of 'style' warnings...  Adding const can't possibly break anything or result in wrong expectations, can it?

Richard.

>nathan

Re: [libibery PATCH] Fix bootstrap

[Jonathan Wakely]

On 25/05/17 14:35 +0200, Richard Biener wrote:
>On May 25, 2017 1:38:36 PM GMT+02:00, Nathan Sidwell <nathan@acm.org> wrote:
>>On 05/25/2017 07:21 AM, Jonathan Wakely wrote:
>>
>>> I don't mind removing the warning again if preferred. I thought it
>>was
>>> useful (as we already warn for ignored const in return types).
>>
>>Oh yeah, I recall noticing we did that (and noting we didn't warn
>>elsewhere).  This new warning seems consistent.
>>
>>I say leave it in unless the grumbling gets too much for you :)
>
>I wonder if we can somehow default to -Wno-error=xyz for such kind of 'style' warnings...  Adding const can't possibly break anything or result in wrong expectations, can it?

Now that G++ correctly ignores the const it can't change (or break)
anything to add const in the cast.

Before I fixed PR 80544, the presence/absence of the const affected
the generated code and could result in e.g. different overloaded
functions being called (in some fairly obscure cases).

The original report I got was http://ideone.com/JSFEZ3 and GCC was
giving different behaviour to all other C++ compilers (which ignored
the const and so failed the static assertion).

The warning is just saying "hey, you know what you wrote is going to
be ignored, right?" That's a bit like "statement has no effect"
warnings, although those warnings are usually because you mistyped
something and so find real bugs.